This invention pertains to ambient type sensors such as photoelectric and ionization smoke detectors. More particularly, the invention pertains to structures for locating the respective sensor/sensors with an orientation that facilitates the ingress of smoke into the sensors
Known smoke detector designs mount the respective sensor inside a housing or on top of the housing. Both ionization and photoelectric sensors have been located inside housings having complicated vents and baffling designs in order to promote the ingress of smoke. Smoke detectors having sensors mounted inside the cover of the detector may have barriers such as the p-horn, battery, or other electrical components that interfere with smoke detection due to interference with smoke flow.
FIGS. 1A-1C illustrate relevant aspects of a prior art smoke detector 10. The detector 10 includes a base 12 intended to be attached to a ceiling C. A cover 14 is carried on the base 12. A plurality of openings indicated generally at 16 provide smoke pathways into and out of the cover 14.
In the detector 10, a printed circuit board 20 is carried adjacent to the mounting base 12. The printed circuit board 20 in turn carries an ambient condition sensor, such as a smoke sensor 22, an audible output device such as a horn or the like 24, and a power supply such as a battery 26. Other electrical or electronic components generally indicated at 28, are conventionally carried by the printed circuit board 20 often on the same side as are sensor 22, horn 24 and battery 26.
The configuration illustrated in FIGS. 1A, 1B and 1C results in convoluted and tortuous smoke flow paths in and out of openings 16 and into cover 14. Placing the sensor 22 on the printed circuit board as in FIGS. 1A, 1B and 1C directs the sensor 22 into the internal volume of the cover 14 away from smoke flow adjacent ceiling C. To compensate for placement of the sensor 22, known detectors have included vents and baffles for the purpose of promoting smoke flow to and from the respective sensor.
It would be desirable from a cost and design manufacturing perspective to be able to eliminate known vents, baffles and flanges. Preferably such reduced complexity might promote improved flow into and out of the respective housings.
The invention takes advantage of both the laminar and turbulent nature of smoke flow. Often smoke detectors are ceiling mounted. The sensor or sensors are arranged within the detector so as to be located near the respective mounting surface, such as near or on the ceiling.
The sensors are carried adjacent to a mounting surface of the detector as opposed to being mounted in the cover as in prior art smoke detectors. The design hereof displaces the sensor/sensors away from electronic components and closer to the mounting surface such as the ceiling. An air sampling gap exposes the sensor/sensors to air and smoke adjacent to the ceiling.
One or more sensors (ionization or photoelectric) may be carried adjacent to the mounting member for the detector. The present invention promotes omni-directional ingress of smoke into the detector.
Unlike the prior art, this invention eliminates the need for complicated venting geometries and complex baffling designs. This follows since the sensors are located adjacent to the mounting surface so as to promote direct ingress and egress of airborne smoke, and thus improved directionality.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.